The effect of lipoproteins in the blood on atherosclerosis is known. When blood cholesterol is high, increasing the risk of atherosclerosis, there is usually an increase in the low-density lipoprotein, LDL, the so-called "bad" cholesterol. High-density lipoproteins (HDL) appear to remove excess cholesterol from the bloodstream and are thus referred to as the "good" cholesterol. Recent work suggests that the HDL-LDL differentiation is not sufficiently precise and some workers are now using other categories; very low density lipoproteins (9VLDL), intermediate density lipoprotein (IDL), etc. The point is that different lipoproteins contribute differently, even within the above gross subdivisions, to the onset and progression of atherosclerosis. Accordingly, a method of quickly identifying the proteins in the bloodstream is advantageous.
Currently, the apolipoproteins are isolated from blood or plasma by density gradient ultracentrifugation followed by organic solvent extraction of the lipid portion of the lipoprotein. The procedure is usually limited by the lengthy period required for the ultracentrifugation step (12-24 hours), as well as by the number of samples that can be processed at any one time. Because of these constraints, only problem patients receive this type of blood analysis.
There are other instances, as well, where it is desired to separate proteins from aqueous solutions thereof. For example, the manufacture of apolipoproteins or other lipid binding proteins by microbiological processes, or their isolation from other biological sources, usually involves an aqueous fermentation or extraction media from which the produced proteins must be recovered. Our invention is nicely applicable to this situation as well.